Final answer:
The glomerular basement membrane (GBM) is part of the kidney's nephron filtration system with three layers that work together to filter blood while blocking larger proteins and cells, creating a filtrate rich in positively charged substances.
Step-by-step explanation:
The glomerular basement membrane (GBM) is a critical part of the kidney's filtration system, located within the nephron. It consists of three layers: the fenestrated endothelium of the capillary, the basement membrane itself, and the filtration slits created by the podocytes. These layers work together to prevent the filtration of blood cells and larger proteins like globulins, while allowing smaller molecules to pass.
The endothelial fenestrations block anything larger than 8nm and repel negatively charged substances due to the negative charge of membrane proteins. The podocytes extend finger-like projections called pedicels that interdigitate, leaving narrow slits for filtration, forming a crucial part of the filtration barrier. This structure ensures that the resulting filtrate contains neither cells nor large proteins, and with a slight predominance of positively charged substances.